ARS | Publication request: Oxidation Kinetics of Biodiesel by Non-Isothermal Pressurized-Differential Scanning Calorimetry

Submitted to: North American Thermal Analysis Society Meeting
Publication Type: Proceedings/Symposium
Publication Acceptance Date: July 1, 2006
Publication Date: July 1, 2006
Citation: Dunn, R.O. 2006. Oxidation kinetics of biodiesel by non-isothermal pressurized-differential scanning calorimetry. In: Proceedings of the 34th Annual Conference of the North American Thermal Analysis Society, August 7-9, 2006, Bowling Green, Kentucky. p. 12-14.

Technical Abstract: Biodiesel, an alternative diesel fuel derived from transesterification of vegetable oils or animal fats with methanol or ethanol, is a mixture of relatively stable (saturated) and oxidatively unstable (unsaturated) long-chain fatty acid alkyl esters. During storage, autoxidation caused by contact with air presents a legitimate concern to fuel producers and consumers seeking to monitor and maintain good fuel quality. Extensive oxidative degradation directly and indirectly compromises fuel quality with respect to kinematic viscosity, acid value, peroxide value and other fuel properties. This work applies non-isothermal pressurized-differential scanning calorimetry (P-DSC) to investigate the oxidation reaction kinetics of biodiesel from soybean oil (SME). Air pressure = 2000 kPa (290 psig) was used to increase the molar concentration of oxygen available for reaction. P-DSC heating scans were conducted with ramp rates (B) varying from 1 to 20 deg C/min to measure oxidation onset temperatures (OT) in both static (closed) and dynamic (flow through) mode. OT results were treated by Ozawa-Flynn-Wall (OFW) analysis to infer activation energy (Ea) and pre-exponential factors (Z) and the results compared with literature values. This work shows the kinetic parameters of biodiesel oxidation obtained from non-isothermal P-DSC analyses may be employed to determine relative resistance to oxidation at any temperature.